Bottom Line:
In the tetra-hydrate, dimers of two [SrO9] polyhedra connected by two sharing water mol-ecules are formed.The structure of the nona-hydrate contains one Sr(2+) cation coordinated by seven water mol-ecules and by two O atoms of two perchlorate tetra-hedra (point group symmetry ..m), forming a tricapped trigonal prism (point group symmetry m2m).O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in each of the three structures.

ABSTRACTThe title compounds, strontium perchlorate trihydrate {di-μ-aqua-aquadi-μ-perchlorato-strontium, [Sr(ClO4)2(H2O)3] n }, strontium perchlorate tetra-hydrate {di-μ-aqua-bis-(tri-aqua-diperchloratostrontium), [Sr2(ClO4)4(H2O)8]} and strontium perchlorate nona-hydrate {hepta-aqua-diperchloratostrontium dihydrate, [Sr(ClO4)2(H2O)7]·2H2O}, were crystallized at low temperatures according to the solid-liquid phase diagram. The structures of the tri- and tetra-hydrate consist of Sr(2+) cations coordinated by five water mol-ecules and four O atoms of four perchlorate tetra-hedra in a distorted tricapped trigonal-prismatic coordination mode. The asymmetric unit of the trihydrate contains two formula units. Two [SrO9] polyhedra in the trihydrate are connected by sharing water mol-ecules and thus forming chains parallel to [100]. In the tetra-hydrate, dimers of two [SrO9] polyhedra connected by two sharing water mol-ecules are formed. The structure of the nona-hydrate contains one Sr(2+) cation coordinated by seven water mol-ecules and by two O atoms of two perchlorate tetra-hedra (point group symmetry ..m), forming a tricapped trigonal prism (point group symmetry m2m). The structure contains additional non-coordinating water mol-ecules, which are located on twofold rotation axes. O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in each of the three structures.

fig2: Formation of chains parallel [100] by sharing water mol­ecules in the structure of Sr(ClO4)2·3H2O.

Mentions:
The crystal structure of strontium perchlorate trihydrate contains two crystallographically distinct Sr2+cations. Both are coordinated by five water mol­ecules and four monodentately bonding perchlorate tetra­hedra (Fig. 1 ▶). Four of the five water mol­ecules (O1, O6 and O3, O4) share edges between two Sr2+ cations, resulting in chains with alternating Sr1 and Sr2 cations. The chains extend parallel to [100] (Fig. 2 ▶). The crystal structure of strontium perchlorate tetra­hydrate is similar to the trihydrate, but different to the magnesium analogue (Robertson & Bish, 2010 ▶; Solovyov, 2012 ▶) or mercury perchlor­ate tetra­hydrate (Johansson et al., 1966 ▶). Two symmetry-related Sr2+ cations, both coordinated by five water mol­ecules and four monodentate perchlorate tetra­hedra, form dimers by sharing two water mol­ecules. In strontium perchlorate nona­hydrate, the Sr2+ cation occupies a single crystallographic site with site symmetry m2m. It is coordinated by seven water mol­ecules and two monodentate perchlorate tetra­hedra (point group symmetry ..m; Fig. 3 ▶a) within a tricapped trigonal-prismatic oxygen coordination environment (Fig. 3 ▶b). Thereby, the trigonal base planes are chosen such that each oxygen atom of the perchlorate anions represents a capping atom. The third cap is provided by a water oxygen atom.

fig2: Formation of chains parallel [100] by sharing water mol­ecules in the structure of Sr(ClO4)2·3H2O.

Mentions:
The crystal structure of strontium perchlorate trihydrate contains two crystallographically distinct Sr2+cations. Both are coordinated by five water mol­ecules and four monodentately bonding perchlorate tetra­hedra (Fig. 1 ▶). Four of the five water mol­ecules (O1, O6 and O3, O4) share edges between two Sr2+ cations, resulting in chains with alternating Sr1 and Sr2 cations. The chains extend parallel to [100] (Fig. 2 ▶). The crystal structure of strontium perchlorate tetra­hydrate is similar to the trihydrate, but different to the magnesium analogue (Robertson & Bish, 2010 ▶; Solovyov, 2012 ▶) or mercury perchlor­ate tetra­hydrate (Johansson et al., 1966 ▶). Two symmetry-related Sr2+ cations, both coordinated by five water mol­ecules and four monodentate perchlorate tetra­hedra, form dimers by sharing two water mol­ecules. In strontium perchlorate nona­hydrate, the Sr2+ cation occupies a single crystallographic site with site symmetry m2m. It is coordinated by seven water mol­ecules and two monodentate perchlorate tetra­hedra (point group symmetry ..m; Fig. 3 ▶a) within a tricapped trigonal-prismatic oxygen coordination environment (Fig. 3 ▶b). Thereby, the trigonal base planes are chosen such that each oxygen atom of the perchlorate anions represents a capping atom. The third cap is provided by a water oxygen atom.

Bottom Line:
In the tetra-hydrate, dimers of two [SrO9] polyhedra connected by two sharing water mol-ecules are formed.The structure of the nona-hydrate contains one Sr(2+) cation coordinated by seven water mol-ecules and by two O atoms of two perchlorate tetra-hedra (point group symmetry ..m), forming a tricapped trigonal prism (point group symmetry m2m).O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in each of the three structures.

ABSTRACTThe title compounds, strontium perchlorate trihydrate {di-μ-aqua-aquadi-μ-perchlorato-strontium, [Sr(ClO4)2(H2O)3] n }, strontium perchlorate tetra-hydrate {di-μ-aqua-bis-(tri-aqua-diperchloratostrontium), [Sr2(ClO4)4(H2O)8]} and strontium perchlorate nona-hydrate {hepta-aqua-diperchloratostrontium dihydrate, [Sr(ClO4)2(H2O)7]·2H2O}, were crystallized at low temperatures according to the solid-liquid phase diagram. The structures of the tri- and tetra-hydrate consist of Sr(2+) cations coordinated by five water mol-ecules and four O atoms of four perchlorate tetra-hedra in a distorted tricapped trigonal-prismatic coordination mode. The asymmetric unit of the trihydrate contains two formula units. Two [SrO9] polyhedra in the trihydrate are connected by sharing water mol-ecules and thus forming chains parallel to [100]. In the tetra-hydrate, dimers of two [SrO9] polyhedra connected by two sharing water mol-ecules are formed. The structure of the nona-hydrate contains one Sr(2+) cation coordinated by seven water mol-ecules and by two O atoms of two perchlorate tetra-hedra (point group symmetry ..m), forming a tricapped trigonal prism (point group symmetry m2m). The structure contains additional non-coordinating water mol-ecules, which are located on twofold rotation axes. O-H⋯O hydrogen bonds between the water mol-ecules as donor and ClO4 tetra-hedra and water mol-ecules as acceptor groups lead to the formation of a three-dimensional network in each of the three structures.